What happened was, Movie Megatron (having been resurrected by Armada Megatron) invited Armada Megs and TFP Starscream to come see the Hatchlings. He promptly set one on Screamer's shoulder (After Screamer had a 'sticky' encounter with Igor) and it immediately liked him.

The Hatchling likes Starscream, Starscream does not like the Hatchling. The Hatchling nuzzled his neck and purred.

Igor. Igor is the tiny little creature that looks like a robot Mr. Potato head, but green and with a tongue like Venoms. He's the little henchmen that follows Megatron around in DOTM when they are in Africa.